Related Experiment Video
Updated: Feb 6, 2026
06:24
High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
6.9K
Spontaneous light-induced Turing patterns in a dye-doped twisted nematic layer.
Ignacio Andrade-Silva1, Umberto Bortolozzo2, Marcel G Clerc1
1Departamento de Física and Millennium Institute for Research in Optics, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla, 487-3, Santiago, Chile.
Scientific Reports
|August 29, 2018
Summary
Light spontaneously forms stripe patterns in liquid crystals via a novel Turing mechanism. This process, driven by photoisomerization of azo-dyes, avoids traditional optical nonlinearities and temporal modulations.
Area of Science:
- Physics
- Materials Science
- Chemistry
Background:
- Optical pattern formation typically relies on diffraction, nonlinearity, or temporal modulation.
- Existing mechanisms often involve Kerr media or photosensitive chemical reactions.
Purpose of the Study:
- To investigate a new mechanism for spontaneous optical pattern formation.
- To demonstrate stripe domain induction in liquid crystals using azo-dyes.
Main Methods:
- Utilized a twisted nematic liquid crystal layer doped with azo-dyes.
- Explored light-induced photoisomerization of dopants.
- Investigated the interplay between dopant transport and nematic order parameter.
Main Results:
- Observed spontaneous stripe domain formation without external modulation.
- Identified a Turing mechanism driven by differing scales of dopant transport and nematic order.
- Developed a theoretical model coupling dopant concentration and nematic order parameter.
Conclusions:
- Established a novel light-induced Turing instability for pattern formation in liquid crystals.
- Demonstrated that photoisomerization of azo-dyes can drive spontaneous pattern generation.
- Highlighted the importance of scale separation in dopant transport and nematic order for pattern emergence.
Related Concept Videos
01:30Spontaneous and Induced Mutations
2.3K
Spontaneous mutations arise infrequently during DNA replication due to errors in the process. A key factor behind these errors is tautomeric shifts in nitrogenous bases, where bases transition from keto to enol forms or amino to imino forms. This shift can alter base-pairing rules, leading to mutations. Additionally, reactive oxygen species (ROS) arising from aerobic metabolism can damage DNA, resulting in depurination (loss of a purine base) or depyrimidination (loss of a pyrimidine base).
2.3K
02:21Spontaneity
30.1K
A spontaneous process is one that occurs naturally under certain conditions. A nonspontaneous process, on the other hand, will not take place unless it is “driven” by the continual input of energy from an external source. Processes have a natural tendency to occur in one direction under a given set of conditions. Water will naturally flow downhill (spontaneous process), but uphill flow (nonspontaneous process) requires outside intervention such as the use of a pump. Iron exposed to...
30.1K
01:13Angle of Twist: Problem Solving
797
An electric motor applies a torque of 700 N·m to an aluminum shaft, triggering a stable rotation. Two pulleys, B and C, are subjected to torques of 300 N·m and 400 N·m, respectively. The modulus of rigidity is provided as 25 GPa. With the knowledge of the length and diameter of each segment, the twist angle between the two pulleys can be computed. First, a section cut is made between pulleys B and C, and the cut cross-section is analyzed using a free-body diagram. Given that the torque...
797
01:13Angle of Twist - Elastic Range
814
Consider a cylindrical shaft with a length denoted by L and a consistent cross-sectional radius referred to as r. This shaft undergoes a torque at the free end. The highest shearing strain within the shaft is directly proportional to the twist angle and the radial distance from the shaft axis. When the shaft behaves elastically, this shearing strain can be articulated using variables such as the applied torque, radial distance, the polar moment of inertia, and the modulus of rigidity. By...
814
01:06Fixed Action Patterns
17.7K
A fixed action pattern (FAP) is a specific, hard-wired sequence of behaviors that occurs in response to an external stimulus, called a sign stimulus. The behavior is “fixed” because it is essentially unchangeable—proceeding similarly across individuals of a species every time it occurs.
17.7K
01:21Layers of the Epidermis
8.4K
The epidermis, the outermost layer of the skin, is composed of several distinct layers. From deep to superficial, the layers of the epidermis are as follows:
Stratum Basale
Stratum basale, also known as the stratum germinativum, is the deepest layer of the epidermis. It is composed of a single layer of actively dividing cells called basal cells or basal keratinocytes. These cells constantly undergo cell division to replenish the upper layers of the epidermis. Additionally, melanocytes, which...
Stratum Basale
Stratum basale, also known as the stratum germinativum, is the deepest layer of the epidermis. It is composed of a single layer of actively dividing cells called basal cells or basal keratinocytes. These cells constantly undergo cell division to replenish the upper layers of the epidermis. Additionally, melanocytes, which...
8.4K